In industrial settings, control systems are used to monitor and control industrial and chemical processes, and the like. Typically, the process control system performs these functions using field devices distributed at key locations in the industrial process and coupled to the control circuitry in the control room by a process control loop. Field devices generally perform a function, such as sensing a parameter or operating upon the process, in a distributed control or process monitoring system.
Some field devices include a transducer. A transducer is understood to mean either a device that generates an output signal based on a physical input or that generates a physical output based on an input signal. Typically, a transducer transforms an input into an output having a different form. Types of transducers include various analytical equipment, pressure sensors, thermistors, thermocouples, strain gauges, flow transmitters, positioners, actuators, solenoids, indicator lights, and others.
Some process installations may involve highly volatile, or even explosive, environments. Accordingly, it is often beneficial, or even required, for field devices and the handheld field maintenance tools used with such field devices to comply with intrinsic safety requirements. These requirements help ensure that compliant electrical devices will not generate a source of ignition even under fault conditions. One example of Intrinsic Safety requirements is set forth in: APPROVAL STANDARD INTRINSICALLY SAFE APPARATUS AND ASSOCIATED APPARATUS FOR USE IN CLASS I, II and III, DIVISION NUMBER 1 HAZARDOUS (CLASSIFIED) LOCATIONS, CLASS NUMBER 3610, promulgated by Factory Mutual Research October, 1998. Examples of handheld field maintenance tools that comply with intrinsic safety requirements includes those sold under trade designations Model 375 Field Communicator and Model 475 Field Communicator, available from Emerson Process Management of Austin, Tex.
Typically, each field device also includes communication circuitry that is used for communicating with a process control room, or other circuitry, over a process control loop. Traditionally, analog field devices have been connected to the control room by two-wire process control current loops, with each device being connected to the control room by a single two-wire control loop. In some installations, wireless technologies have begun to be used to communicate with field devices. Wireless operation simplifies field device wiring and set-up.
One wireless process communication technology standard is known as the WirelessHART standard. The WirelessHART standard was published by the HART Communication Foundation in September 2007. Relevant portions of the Wireless HART® Specification include: HCF_Spec 13, revision 7.0; HART Specification 65—Wireless Physical Layer Specification; HART Specification 75—TDMA Data Link Layer Specification (TDMA refers to Time Division Multiple Access); HART Specification 85—Network Management Specification; HART Specification 155—Wireless Command Specification; and HART Specification 290—Wireless Devices Specification.
Another wireless network communication technology is set forth in ISA100.11a. This technology proposes wireless communication at the 2.4 GHz frequency using radio circuitry in accordance with IEEE 802.15.4-2006. The ISA100.11 standard is maintained by the International Society of Automation (ISA).
While these wireless communication technologies provide important advantages to the art of process control and communication, traditional techniques for maintaining and configuring wireless field devices that employ such communication is sometimes rendered inefficient.